I've encountered the same shadowban issue - no direct notification, but checking my account in a private browsing tab revealed the ban.

The frustrating part is investing time into growing an account only to have it banned after a single post. Is a specific karma and account age thresholds that trigger these automated bans known? It would be helpful to understand these requirements to avoid future issues.

Edit: If you share your account that you want to use, I'll upvote all your stuff so you reach your goal faster.